Understanding
the UL Fire Resistance Directories
Trusses:áá Parallel chord trusses, spaced a max of
24 in.á OC fabricated from nom 2 by 4
lumber, with lumber oriented vertically or horizontally. Min truss depth is 18
in.á Truss members secured together with
min 0.0356 in. thick galv steel plates.á Plates have 5/16 in.
long teeth projecting perpendicular to the plane of the plate.á The teeth are in pairs facing each other
(made by the same punch), forming a split tooth type plate.á Each tooth has a chisel point on its outside
edge.á These pairs are repeated on
approx. 7/8 in. centers with four rows of teeth per inch of plate width.
2
3
Batts and Blankets:á Glass fiber insulation, max 3 û ╜ in.
thick, fitted in the concealed space, draped over the resilient channels and
gypsum wallboard ceiling membrane.á Any glass fiber
insulation bearing the UL Classification Marking as to Surface Burning
Characteristics and/or Fire Resistance, having a min density of 0.5 pcf.